Moisture Safety Research Articles

Enhancing CLT construction – Hygrothermal modelling, novel performance criterion, and strategies for end-grain moisture safety

This study validated a 2D dynamic anisotropic hygrothermal simulation model for Cross-Laminated Timber (CLT), focusing on vertical water uptake and moisture dry-out processes. The simulations, compared against experimental data, showed a root mean square deviation of ≤3.3 across all locations. Variations in material properties necessitated the use of multiple material definitions. Moisture storage and liquid conductivity function had a significant impact on the results. A new two-step moisture content (MC) performance criterion was developed: MC ≤ 16 % at 30 mm and MC ≤ 25 % at 10 mm from the end grain to prevent mould growth. Sensitivity analysis suggested that validating MC30 mm is reasonable when MC10 mm exceeds 19 %. The criterion was applied to analyse moisture management strategies for CLT end-grain moisture safety. Simulations with 30-year climate data indicated a slight decrease in successful outcomes in recent years. Strategic installation timing, particularly favouring the spring season due to its relatively drier conditions in Estonia, was found to be highly beneficial. CLT end-grain protection or full-coverage weather protection is recommended to ensure a high level of moisture safety, and long construction periods should be avoided even with full-coverage protection. Including moisture dry-out periods before covering CLT is advised. However, unassisted dry-out is feasible only during spring (up to four weeks). Additional equipment is necessary for timely moisture dry-out during other seasons, including summer, due to higher precipitation loads. The use of anisotropic 2D hygrothermal simulations proved to be practical in enhancing CLT resilience to moisture-induced damage.

Predictive modeling and estimation of moisture damages in Swedish buildings: A machine learning approach

Identifying potential moisture damage is crucial for maintenance practices and assurance of well-being of occupants. However, due to limited information availability and standardization, assessing damage prevalence on the building stock scale remains understudied. By combining investigation records and building databases, this study leverages data analytic techniques and machine learning modeling to characterize damage pathology and predict its occurrence in Swedish buildings. The interrelationships between damage-specific attributes and their associations with building parameters of several damage types were analyzed using feature selection, forming the basis for developing predictive models. Results show that multilabel classifiers outperform binary classifiers for every damage type, with lead tree ensemble models achieving minimum average AUCPR and F2 of 0.85 for microbial growth, 0.87 for deformation, 0.91 for odor, and 0.95 for water leakage. The identified patterns were interpreted and verified against descriptive statistics. The binary relevance models estimate that one-third of school buildings, 20% of commercial and office buildings, and 15% of residential dwellings in regional building stock contain moisture damage. These findings advance the quantification of moisture damage by providing new knowledge and approaches for appraising moisture damage likelihood at aggregated and individual building levels, thereby aiding in moisture safety evaluations and preventive maintenance efforts.

Future Climate Projections and Uncertainty Evaluations for Frost Decay Exposure Index in Norway

To implement the geographical and future climate adaptation of building moisture design for building projects, practitioners need efficient tools, such as precalculated climate indices to assess climate loads. Among them, the Frost Decay Exposure Index (FDEI) describes the risk of freezing damage for clay bricks in facades. Previously, the FDEI has been calculated for 12 locations in Norway using 1961–1990 measurements. The purpose of this study is both updating the FDEI values with new climate data and future scenarios and assessing how such indices may be suitable as a climate adaptation tool in building moisture safety design. The validity of FDEI as an expression of frost decay potential is outside the scope of this study. Historical data from the last normal period as well as future estimated climate data based on 10 different climate models forced by two emission scenarios (representative concentration pathways 4.5 and 8.5) have been analyzed. The results indicate an overall decline in FDEI values on average, due to increased winter temperatures leading to fewer freezing events. Further, the variability between climate models and scenarios necessitates explicit uncertainty evaluations, as single climate model calculations may result in misleading conclusions due to high variability between models.

Carbon Footprints of a Conventional Norwegian Detached House Exposed to Flooding

Rehabilitating water-damaged structures in buildings results in increased material extraction and energy use, and, consequently, a higher carbon footprint of the housing industry. Despite its prevalence, quantifying the carbon footprint caused by water damage or flooding has not gained much attention. Thus, this study investigated the quantitative carbon footprint associated with rehabilitating flooding in a detached house caused by torrential rain. Three different construction methods of the house were looked at; a timber frame construction, a masonry variant made by concrete blocks of Lightweight Expanded Clay Aggregate (LECA), and an alternative with exterior walls composed of concrete-moulded Expanded Polystyrene (EPS) foam boards. A life-cycle assessment according to NS 3720 was used to investigate the carbon footprint (CO2eq.) of typical flooding in a detached building. Rehabilitating the flooding in a house with concrete-moulded boards resulted in a lower carbon footprint (2.45 × 103 CO2eq.) than rehabilitating the same flooding in a house with LECA masonry (7.56 × 103 CO2eq.) and timber frames (2.49 × 103 CO2eq.). However, the timber-frame house had the lowest total carbon footprint (2.95 × 104 CO2eq.) owing to their original low footprint. This study found that flooding significantly contributed to the carbon footprint of buildings and, therefore, the topic should be given attention when choosing a construction method and moisture safety strategy.

Moisture Safety in Prefabricated Roof Renovations: Causes and Strategies

Achieving carbon neutrality by 2050 requires extensive energy renovation of the existing building stock. In this study we focus on deep renovation with prefabricated insulation elements as a potential solution to attain the required renovation speed and volume. The use of such elements without a proper moisture safety strategy can, however, lead to moisture-related problems, including mould growth. Here we examine the causes of moisture and mould damage in a case study of a building that has been renovated to near-zero energy standards using prefabricated insulation elements. The study elucidates the reasons for the moisture damages detected and proposes two moisture safety strategies to improve the situation. The first strategy emphasizes the importance of ensuring dry construction conditions by either using a full temporary roof or avoiding rainfall during installation. The second strategy addresses localized water damage to the attic floor and involves the use of protective measures, active ventilation and a correct installation sequence. In the case of local moisture damage, the required amount of ventilation air flow during summer is 0.5–0.55 l/(s·m²). During cooler periods, heating is needed. The employed methods include modelling the case-study building with the IDA Indoor Climate and Energy software, as well as mould growth risk assessment based on temperature and relative humidity measurements. The results highlight the effectiveness of both strategies in preventing mould growth if applied correctly, and emphasize the need for thorough planning, moisture safety regulations and rapid response to ensure successful renovation with prefabricated insulation units. The study provides valuable information on moisture safety strategies for serial renovations with prefabricated elements. The existence and proper implementation of a moisture safety strategy is important for achieving the desired energy performance goals while maintaining building durability and occupant health, and it needs to be applied throughout the chain of site management: from the main contractor down to the skilled worker.

Development of Prefabricated Additional Insulation Elements for the Renovation of High-Rise Apartment Buildings

Prefabricated additional insulation elements have demonstrated success in renovating up to 5-storey apartment buildings. However, the unique challenges posed by high-rise buildings necessitate a closer examination of installation and long-term performance. In this study, we developed an additional insulation element specifically tailored for renovating high-rise apartment buildings and analysed its hygrothermal performance. To test the performance of the insulation elements, we installed a prototype and measured its performance at critical points along the external envelope. We calibrated a calculation model and applied building performance simulation software to explore various combinations of prefabricated elements. Our goal was to compare the associated risks and the key hygrothermal properties of these different material combinations within the insulation element. Critical points between the insulation layer and the wind barrier, as well as between the surface of the existing concrete panel wall and the vapour control layer of the additionally insulated exterior wall were analysed. The study's results indicate that the thermal resistance and water vapour permeability of the wind barrier layer, and the presence of an appropriate vapour control layer primarily influence the performance and moisture dry-out of a structure. Additionally, the study results indicate that the weather component has a higher impact than in lower buildings as the wind-driven rain loads are considerably higher in the upper parts of the high-rise buildings. The initial moisture (w = 110 kg/m3 at the height of the 9th storey and w = 117 kg/m3 at the height of the 16th storey) dry-out can last more than 3 years depending on the building type and materials used. This study underscores the importance of tailored solutions and vigilant moisture safety management in high-rise apartment building renovations, particularly when utilizing prefabricated additional insulation elements.

Hygrothermal assessment and design models for mass timber building envelopes in northern conditions

Log construction has a long and rich tradition in Northern Europe, yet the rising demand for energy-efficient log housing poses challenges for designers seeking optimal hygrothermal performance. One proposed solution involves utilizing a double-log structure, integrating thermal insulators between two log layers to maintain heritage while enhancing thermal resistance. This study addresses the complexities of designing energy-efficient log buildings in cold and arctic conditions and investigates steady-state and dynamic approaches to hygrothermal assessments. Emphasizing various cold climate scenarios, hygrothermal design intricacies, moisture safety considerations, and critical parameters impacting building performance, the research fills knowledge gaps in design strategies and highlights the risks associated with the double-log structure.

A Numerical Study of Methods to Improve Moisture Safety of Ventilated Wooden Roofs

The hygrothermal performance of highly insulated, prefabricated wooden roof structures is likely to deteriorate due to the low heat flux to the ventilation cavity. This article evaluates the possibility to improve the moisture safety of such roofs in a Nordic climate by using different control methods for the ventilation rate of the roof and by using thermal insulation above the roof sheathing. The results support the use of adaptive roof ventilation as it decreases the probability of mould growth in the roof. The use of thermal insulation above roof sheathing decreases the probability of mould growth only slightly in a roof with elevated amount of built-in moisture.

Barriers to climate adaptation in Norwegian building projects – Insights from moisture safety designers’ perspective

To reduce the escalating maintenance costs for the Norwegian building stock, adapting new building designs to future climate changes becomes necessary. Currently, climate adaptation of moisture safety design by considering future climate loads is not mandatory in the Norwegian building code. This forces building designers to choose between adhering to existing standards and guidelines or investing additional efforts in adapting the building design to future climate change, at higher initial costs and with uncertain long-term benefits. This study aims to analyze the perceptions of Norwegian building physicists of future climate risks and their capacity to influence adaptation efforts in new construction projects. A thematic analysis of 15 semi-structured interviews with Norwegian building physicists from multiple companies and different regions of Norway is presented. The respondents recognize the need to adapt building designs to account for future climate loads more effectively; however, they lack the requisite influence and tools to implement the same. They look to authorities to establish requirements, and research institutes to develop tools that enable them to effectively fulfil their roles. Significant barriers for climate adaptation in building projects include lack of support from other project stakeholders, unavailability of efficient tools based on qualitative risk assessment for addressing climate adaptation, and insufficient focus on climate adaptation in building codes and guidelines. Development of methods for implementing climate adaptation in moisture safety design must reflect this, and quick-to-use robusteness assessment frameworks that treats these uncertainties in a non-quantitative manner are needed.

Internal Insulation – four systems in one historic residential building

Reducing the heat loss from European buildings must include thermal retrofitting of the historic buildings. In these cases, where buildings have facades worthy of preservation, internal insulation is the only solution although external insulation is better hygrothermal solution. Inspections in buildings with internal insulation have in multiple cases shown mold growth problems at the intersection between the original wall and the insulation. Thus, there is a need for real-life testing; i.e., raising the level of reality by using professional craftsmen to apply internal insulation to existing buildings inhabited by ordinary users. Building owners are more likely to accept these solutions when they have been tested in reality, and not only in the lab or with simulations, on efficiency, robustness, and moisture safety. In Denmark, the older, worthy-of-preservation, historic buildings are commonly built with solid masonry facades. Consequently, internal insulation might involve hygrothermal risks for the external walls. The present study describes a case study of a typical historic building built in 1837. In specific, the paper focuses on the top (5th) floor of the building, which is a residential area (a commune). On the 5th floor, four different types of insulation materials were installed in eight different rooms. The performance of the four insulation materials was determined by monitoring the temperature and relative humidity at the intersections between the insulation and the existing wall, as well as the indoor and outdoor climate. Results of the measurements of the available period showed that relative humidity is increasing for most of the sensors, with an exception of a few sensors that appear to have decreased values compared to the first month. Furthermore, the risk of mold growth was calculated with the VTT mold growth model based on performed measurements and indicated minimum to non-existent mold growth risk so far.

Impact of indoor humidification on hygrothermal performance of building envelope in Northern Finland

Dry indoor air is known to increase the risk for respiratory infections, viability, transport of influenza virus and intensifies sensitivity of nasal systems. The aim of this study was to investigate the effect of humidification on the hygrothermal performance of the common timber wall structure of a day care building located in Northern Finland. Hygrothermal performance of structures under different indoor moisture loads was analysed. Numerical simulation and the Finnish mould growth model were used to evaluate the impact of humidification on moisture safety of the envelope. Largest impact of indoor air humidification is observed in the low humidity ranges on inner side of water vapour barrier. At the outer side of the water vapor barrier the indoor humidification has no effect on the hygrothermal conditions or mould growth risk. The most favourable conditions for mould growth are obtained at the corner of the building envelope, at the interface of load bearing timber and windshield where hygrothermal conditions are almost 60% of the time over 80% of relative humidity. However, the Finnish mould index does not indicate any mould growth risk. The study demonstrates that the indoor air can be humidified to RH of 35% during the cold dry period.

Hygrothermal Performance of Prefabricated Insulation Elements for Serial Renovation of Apartment Buildings in a Moderately Continental German Climate

The reduction of energy use in the buildings is expected to be reached by fulfilling several requirements of the low- and nearly-zero energy buildings (nZEB) policy. The improvement of the energy performance of the building envelope and the service systems of the existing buildings offers great potential for energy savings as the annual replacement of the existing stock is only 1 to 2%. The efficient way to accomplish the purpose and global goals of the nZEB is to apply the integrated design process, development, and application of prefabricated insulation elements on a large scale. In this project, in the Berlin area of Germany, prefabricated timber frame insulation elements were designed for the external insulation of the envelope of the apartment building in the serial renovation process, with the thermal transmittance of the external envelope U external-wall = 0.14–0.16 W/(m2·K). In the current study, the potential hygrothermal risks and their effect on highly insulated multi-story apartment building envelope were analyzed. The study contained a set of hygrothermal analyses to ensure the moisture safety of highly insulated facade structures and the selection of materials from the perspective of hygrothermal performance and low risk of degradation. This research found that the risk of mold growth is high if timber elements are installed without protective measures against drying-out built-in moisture, wind-driven rain, and other weather conditions. The initial moisture content of the external concrete slab, to be considered critical, is 90 kg/m3, and the drying out period is longer than the covered with new layers constructions can sustain if a proper vapor control layer is not added between the existing moist wall and installed insulation elements. Furthermore, the wind barrier layer with high thermal resistance and vapor permeability of the installed insulation element helps to minimize the risk of mold growth. A careful analysis and selection of materials allow to design moisture-safe timber frame insulation elements and provide low thermal transmittance of renovated building envelopes. The results showed that before the final design and installation of the insulation elements, a thorough hygrothermal analysis of the original external envelope with actual climatic conditions and moisture loads must be realized.

Hygrothermal performance of a CLT Ice Sports Arena in a Nordic climate

Indoor ice sports arenas are complex buildings that typically consume large amounts of energy. The energy is mainly used to freeze the ice rink and to keep the indoor air temperature and relative humidity at appropriate levels. Reducing the energy consumption and the carbon footprint from construction, operation, and material use, presents certain challenges from a building physics point of view. These challenges are especially prominent if the ice sports arena is operated in a climate featuring summer seasons that are warmer than the indoor air temperature and winter seasons that are colder. This study investigates the hygrothermal performance of an ice sports arena built using cross-laminated timber (CLT), located in Sandefjord, Norway. Hygrothermal simulations of the exterior wall were conducted and analysed using WUFI. Locally retrieved weather data is compared to WUFI simulations done in the design process, which were based on Moisture Design Reference Year (MDRY) files for Oslo. The moisture performance of the wall as built is investigated for three different indoor temperatures. Modifications to the wall to improve moisture performance are also investigated. Results indicate that the MDRY files do not accurately reflect the climate on site. The performance of the wall assembly is found to depend greatly on indoor temperature. For indoor temperatures colder than 12 °C, substantial condensation and moisture problems are predicted during summer. None of the investigated modifications are found to sufficiently increase the moisture performance of the wall. Drastic measures may be required to improve moisture safety.

Moisture safety strategy for construction of CLT structures in a coastal Nordic climate

To reduce the carbon impact of new buildings, wood is seeing increased use as a structural material. Cross-laminated timber (CLT) and glue-laminated wood (glulam) elements allow the construction of multi-storey buildings. However, wood is vulnerable to moisture, especially when naked wood is exposed to weather during the construction process. This paper presents the moisture strategy employed during the construction of a four-storey CLT/glulam building in Trondheim, Norway. The building was constructed without the use of a weather-protective tent, requiring alternative protective measures. The construction of the main structure was scheduled to be as short as possible. Local protective measures were employed to protect the structure from rain and free water was removed after rain events. The project was closely supervised by the client, with particular care for moisture control. Moisture was regularly measured at 50 points throughout the building. No wooden surfaces were encapsulated until a wood moisture content below 15 weight-% was measured. The performance of the moisture strategy was evaluated using measurements of wood moisture, indoor climate, airtightness, and visual inspections. The wood moisture content quickly decreased as the building envelope was assembled, indicating that drying was well facilitated. In the first year after construction, gaps between the flooring and baseboards were observed, suggesting that the wooden elements have experienced some shrinkage. The moisture safety strategy is deemed to have been generally successful. The overall experiences were important in the development of new recommendations in the SINTEF Building Research Design Guides for CLT structures.

Assessment of Mould Risk in Low-Cost Residential Buildings in Urban Slum Districts of Surakarta City, Indonesia

Prolonged exposure to indoor dampness in dwellings triggers excessive mould, causing health problems for residents and damage to building structures. This study investigated dampness and mould growth in low-cost dwellings in the slum districts of Surakarta, Indonesia. A VTT mould growth model predicted mould risk in 17 dwellings by employing a set of time-series data of indoor air temperature and relative humidity (RH). Interviews were conducted with 11 houses to understand the residents’ perceptions and lifestyles related to mould risk. The daily average dampness (RH > 80%) ranged from 2.2 to 12.3 h. Low-cost dwellings with plywood board walls had a high risk of cumulative mould growth. Statistical correlation analysis revealed that volumetric heat capacity was significantly positively correlated with mould growth at higher percentiles (75th and 97.5th). Thus, dwellings with smaller volumes and plywood board walls were more susceptible to moulding. Moreover, the majority of the participants expressed dissatisfaction with indoor air quality owing to the presence of unpleasant odours from sewage and dampness, which coincided with their perception of inadequate air ventilation. This study provides a reference for developing standard guidelines for building and upgrading dwellings in Indonesia, focusing on assessing and mitigating mould risks and ensuring moisture safety.

Novel water penetration criterion for clay brick masonry claddings

• Investigated water absorption and water penetration in clay brick masonry. • Prepared masonry triplets with three different joint profiles for experiments. • Measure no water penetration till water content exceeds 90% of saturation capacity. Despite the impact of water penetration on the performance of building envelopes, no general agreement is available on implementing water penetration due to wind-driven rain (WDR) in hygrothermal and moisture safety analyses. This study proposes a novel criterion for water penetration in clay brick masonry that depends on the water content level of masonry. An experimental campaign investigating water penetration in clay brick masonry exposed to uniform water spray is conducted on masonry triplets prepared from bricks with different water absorption properties and three mortar joint profiles. During each test, water absorption and water penetration are registered continuously. The results show that no water penetration occurs unless the water content of the specimens is above 90% of their saturation capacity. The saturation level at which penetration starts is consistent across all joint profiles and brick types. Accordingly, exposure to driving rain at levels below the threshold may not lead to water penetration. The utility and implications of the proposed criterion are briefly demonstrated by analyzing water content and water penetration in a clay brick masonry façade. The resulting water penetration is compared with the results obtained using a commonly accepted reference model that assumes one percent of all wind-driven rain deposited on the façade to penetrate the clay brick cladding. By linking water penetration in clay brick masonry to the water content, the proposed criterion is an attempt to logically explain a phenomenon of high scientific and practical relevance for moisture analyses of a frequently used type of building envelope.

Moisture-resilient performance of concrete basement walls – Numerical simulations of the effect of outward drying

The moisture safety designs of basements used for habitation have become a topic of concern. Basements are prone to high moisture strain and have a limited outward drying ability compared with above-grade structures. The risk of interior moisture-related damage can be reduced if the basement walls are allowed to dry outward below grade. The use of vapour-permeable thermal insulation and the effect of air gaps behind dimpled membranes on the outward drying of concrete basement walls were investigated in this study. One- and two-dimensional hygrothermal simulations were conducted using WUFI®Pro and COMSOL Multiphysics®. First, the outward drying of concrete wall segments, previously investigated in a laboratory experiment, was simulated. Two EPS types and two dimpled membrane positions were compared, with an emphasis on the airflow through the air gap behind the membrane. Second, the long-term moisture performance of concrete basement walls was simulated. It was observed that when the dimpled membrane was placed between the concrete and exterior EPS, the bottom of the concrete segments dried faster than the top. When the dimpled membrane was placed on the exterior side, the concrete dried more uniformly along the height. Thus, the results indicated that the latter ensured outward drying of the concrete basement walls. However, the overall effect on the interior RH depended on the characteristics of concrete and the amount of interior and exterior insulation. Optimum drying was achieved when the thickness of interior insulation was reduced. The variability of the concrete properties used in basement walls requires further investigation.

Wetting circumstances, expected moisture content, and drying performance of CLT end-grain edges based on field measurements and laboratory analysis

The moisture safety of cross-laminated timber (CLT) has gained attention as a result of feedback from construction sites and efforts have been made to protect CLT panel surfaces from wetting. However, the end-grain water absorption of CLT has often been overlooked. This study presents data from six CLT buildings where systematic moisture content (MC) measurements were made from when the CLT panels were installed until the commissioning of the buildings. Field measurement results were verified in a laboratory test where moisture uptake and moisture dry-out were monitored. On-site measurements showed that the wetting of CLT end-grain edges was common. Moisture absorption was detected in the end-grain edges in all the studied buildings and often MC > 25% persisted for many months until specific heating or drying was applied. Critical MC occurred after single rain events which suggests that a fast construction process is not always enough to avoid moisture ingress. Protection foils or membranes on the CLT panel faces did not help avoid end-grain wetting in the CLT joints. Protruding details such as floor panels or rubber bands under wall panels facilitated water intrusion. Areas with the CLT end grain exposed to ambient air experienced delamination post wetting. Laboratory test results confirmed very limited moisture dry-out in a typical CLT wall to floor joint but a potential to dry-out if the end-grain edges were exposed to dry and warm air. Specific methods to block water absorption into CLT end-grain edges should be used and joint detailing is crucial.

Monitoring outward drying of externally insulated basement walls: A laboratory experiment

Basements used for habitation represent a major challenge in terms of moisture safety design; they are prone to high moisture strain and have a limited ability for outward drying compared to structures above grade. Exterior vapour-permeable thermal insulation is used in countries with cold climates to enable outward drying. However, its effect is not well documented when combined with a dimpled membrane. A laboratory experiment was performed to investigate the outward drying of concrete walls and to generate data for the validation of hygrothermal simulations. Two wall segments with vapour-permeable insulation and exterior dimpled membranes were compared with a segment having a dimpled membrane positioned between the concrete and exterior insulation. The segments were subjected to a steady warm interior and a cold exterior climate in a climate simulator. Weight change, precipitated condensation, and temperature data were monitored for six months. Although the weights varied nonuniformly at the start, they decreased uniformly during the last four months; they exhibited the same rate and variations of weight change. No precipitated condensation occurred in the air gaps, although the moisture content of the concrete was high and the driving potential for diffusion (temperature gradient) was large. Results indicate that the concrete's ability to transfer moisture to the drying surface limits outward drying. Hence, the vapour permeability of the insulation and the membrane position were less influential. The moisture transfer properties of concrete currently used in basements should be investigated to better predict the long-term moisture performance of products and solutions for basements.

Moisture safety in ventilated cathedral roofs

Cathedral roofs are commonly used when constructing small houses in Sweden. In contrast to roof constructions with a cold attic, where frequent moisture damage has been noted, the cathedral roof is difficult to access for inspection. Furthermore, Swedish building regulations sets high demands regarding moisture safety, although there are no clear guidelines for their compliance. Hence, designing a cathedral roof must be done with great care. Previous studies investigating moisture safety in cathedral roofs, applies a constant air exchange in the ventilated air cavity. In this study a cathedral roof, ventilated from eave to eave, was analysed by examining the relevance of considering the variation in cavity air flow when conducting coupled heat and moisture calculations. The varied cavity air flow was calculated in an air flow model, considering wind and thermal buoyancy as driving forces. The accuracy of moisture safety assessments using the MRD model via hygrothermal calculations in WUFI Pro were also studied. Comparing moisture calculations with measurements showed high similarity when using a model with constant cavity air flow, and even higher resemblance when using a model with varied air flow. When actual conditions are sought, the study indicated that pinpointing important parameters, such as initial moisture content and moisture related material properties, would further increase precision in moisture calculations.